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Moffat MOG (Scalar-Tensor-Vector Gravity) vs Skordis-Złośnik Aether Scalar-Tensor

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	Moffat MOG (Scalar-Tensor-Vector Gravity) Frontier	Skordis-Złośnik Aether Scalar-Tensor Frontier
Proposed	2006	2021
Key figures	John Moffat	Constantinos Skordis, Tom Złośnik
In one sentence	Moffat's 2006 Modified Gravity (MOG, also called STVG) adds a vector field and scalar-field\|scalar fields to general relativity, effectively making Newton's gravitational coupling run with scale. It claims to explain galaxy rotation curves and cluster dynamics without dark matter, but the analyses are largely confined to one research group.	Skordis and Złośnik's 2021 relativistic MOND theory is constructed from the start so that tensor modes propagate at light speed. It reproduces MOND galaxy-scale phenomenology while passing GW170817 by design.
Predictions	Galaxy rotation curves reproduced with effective scale-dependent gravity, no dark halos required Cluster mass profiles and light-bending (lensing) patterns should be explained by visible matter plus MOG's scale-dependent gravity, with no dark matter, the real test being whether one fixed set of MOG parameters works across many clusters rather than being retuned for each Specific deviations from GR at intermediate (galactic, cluster) scales; near-GR behavior in the solar system	Galaxy dynamics reproduce MOND at low accelerations, including the radial acceleration relation Tensor mode propagation speed equals c exactly, by construction (no GW170817 conflict) The cosmic microwave background's acoustic peaks and the way galaxies cluster on large scales should show measurable deviations from ΛCDM; the exact numbers await fitting the theory to all the major datasets at once
Where it breaks	Many MOG fits use system-specific parameter values; critics argue this is parameter-fitting rather than unique theoretical prediction The [[bulk]] of MOG papers come from one research group; independent reproductions of the claimed cluster and lensing fits are scarce in the broader literature Cosmological survey pipelines (DESI, KiDS, DES, Euclid) do not include MOG as a baseline analysis; mainstream cosmology has not adopted the framework Like other modified-gravity proposals, MOG faces the Bullet Cluster (Clowe et al 2006) and CMB acoustic-peak challenges shared across the family	A full global fit to CMB plus BAO plus supernovae plus galaxy data has not been completed; the framework is too young to know if it can match all data simultaneously Like TeVeS, the theory adds extra fields and free functions; some critics see it as replacing [[dark matter]] with an equally elaborate modified-gravity sector The galaxy-scale success is real, but it is inherited from MOND-original, and so are MOND's unsolved problems: the theory still faces the cluster-scale mass gap (Bullet Cluster) and the CMB acoustic-peak fit, neither of which Skordis-Złośnik has yet shown it resolves Without a unique microscopic motivation for the specific field content, the theory is hard to falsify in a sharp sense
Key unresolved problem	The independent-reproduction gap: almost all of MOG's successful fits to galaxy clusters, gravitational lensing, and collisions come from Moffat's own group, and outside teams have not confirmed them, so the wider community has not adopted the theory.	The untested-at-scale problem: no one has yet checked the Skordis-Złośnik theory against all the big cosmological datasets at once, the cosmic microwave background, galaxy surveys, supernovae, and sound-wave imprints (BAO), so we cannot tell if it explains everything ΛCDM does.
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Moffat MOG (Scalar-Tensor-Vector Gravity)

2006 · Frontier

Skordis-Złośnik Aether Scalar-Tensor

2021 · Frontier

Proposed

2006

2021

Key figures

John Moffat

Constantinos Skordis, Tom Złośnik

In one sentence

Moffat's 2006 Modified Gravity (MOG, also called STVG) adds a vector field and scalar-field|scalar fields to general relativity, effectively making Newton's gravitational coupling run with scale. It claims to explain galaxy rotation curves and cluster dynamics without dark matter, but the analyses are largely confined to one research group.

Skordis and Złośnik's 2021 relativistic MOND theory is constructed from the start so that tensor modes propagate at light speed. It reproduces MOND galaxy-scale phenomenology while passing GW170817 by design.

Predictions

Galaxy rotation curves reproduced with effective scale-dependent gravity, no dark halos required
Cluster mass profiles and light-bending (lensing) patterns should be explained by visible matter plus MOG's scale-dependent gravity, with no dark matter, the real test being whether one fixed set of MOG parameters works across many clusters rather than being retuned for each
Specific deviations from GR at intermediate (galactic, cluster) scales; near-GR behavior in the solar system

Galaxy dynamics reproduce MOND at low accelerations, including the radial acceleration relation
Tensor mode propagation speed equals c exactly, by construction (no GW170817 conflict)
The cosmic microwave background's acoustic peaks and the way galaxies cluster on large scales should show measurable deviations from ΛCDM; the exact numbers await fitting the theory to all the major datasets at once

Where it breaks

Many MOG fits use system-specific parameter values; critics argue this is parameter-fitting rather than unique theoretical prediction
The [[bulk]] of MOG papers come from one research group; independent reproductions of the claimed cluster and lensing fits are scarce in the broader literature
Cosmological survey pipelines (DESI, KiDS, DES, Euclid) do not include MOG as a baseline analysis; mainstream cosmology has not adopted the framework
Like other modified-gravity proposals, MOG faces the Bullet Cluster (Clowe et al 2006) and CMB acoustic-peak challenges shared across the family

A full global fit to CMB plus BAO plus supernovae plus galaxy data has not been completed; the framework is too young to know if it can match all data simultaneously
Like TeVeS, the theory adds extra fields and free functions; some critics see it as replacing [[dark matter]] with an equally elaborate modified-gravity sector
The galaxy-scale success is real, but it is inherited from MOND-original, and so are MOND's unsolved problems: the theory still faces the cluster-scale mass gap (Bullet Cluster) and the CMB acoustic-peak fit, neither of which Skordis-Złośnik has yet shown it resolves
Without a unique microscopic motivation for the specific field content, the theory is hard to falsify in a sharp sense

Key unresolved problem

The independent-reproduction gap: almost all of MOG's successful fits to galaxy clusters, gravitational lensing, and collisions come from Moffat's own group, and outside teams have not confirmed them, so the wider community has not adopted the theory.

The untested-at-scale problem: no one has yet checked the Skordis-Złośnik theory against all the big cosmological datasets at once, the cosmic microwave background, galaxy surveys, supernovae, and sound-wave imprints (BAO), so we cannot tell if it explains everything ΛCDM does.

Reader vote

No votes yet